Fine processing by lithography using photoresist compositions has conventionally been performed in manufacturing of semiconductor devices. The fine processing is a processing method of forming a thin film of a photoresist composition on a substrate being processed such as a silicon wafer, irradiating the resultant thin film with an active ray such as an ultraviolet ray through a mask pattern in which a pattern of a semiconductor device is depicted for development, and etching the substrate being processed such as a silicon wafer with the resultant photoresist pattern as a protection film. With the high integration of semiconductor devices in recent years, the active ray used tend to have shorter wavelengths, for example, from KrF excimer laser light (248 nm) to ArF excimer laser light (193 nm). Accordingly, the influence of diffuse reflection of the active ray on the substrate or standing waves has become a serious problem. The use of an anti-reflective coating (Bottom Anti-Reflective Coating, BARC) between the photoresist and the substrate being processed, therefore, has been widely studied.
In the future, with further refinement of resist patterns, a problem of resolution or collapse of resist patterns after development should arise to cause a demand for reducing the film thickness of resists. It is therefore difficult to obtain a resist pattern film thickness sufficient for processing the substrate, and there arises a need for a process that allows not only the resist pattern but also the resist underlayer film formed between the resist and the semiconductor substrate being processed to function as a mask during the substrate processing. There is a growing demand, as a resist underlayer film for such a process, unlike conventional high etch-rate (high etching rate) resist underlayer films, for a resist underlayer film for lithography having a dry etching rate selectivity close to that of the resist, a resist underlayer film for lithography having a dry etching rate selectivity smaller than that of the resist, or a resist underlayer film for lithography having a dry etching rate selectivity smaller than that of the semiconductor substrate (see Patent Document 1).